cutting leather.
Im a bit confused in those post as are a lot of contradictions, so I suppose its down to preference and personal testing. Id like to figure out if the micro serrations on lower grits like 1k japanese actually help to cut like into the tougher grain of the leather and once it is past it glides through or if thats a myth since some say that polished edges are better in piercing.
Il check out those posts more thoroughly but i always end up scratching my head with more questions.
If one searches for 'leather knives', many of them are pretty similar to X-acto blades. Main theme among them seems to be a very THIN grind, and perhaps a chisel-ground edge.
If using EDC-style knife blades for leather, with more typical edge geometry, I'd still at least opt for a more polished finish on the edge bevels, to minimize friction.
David
OWE for the win.
DavidL41, I've worked as a research scientist for over 20 years, most of it in an applied engineering setting and think I understand your confusion.
In short, I think you asked the wrong question at the very outset by focusing on one aspect of blade set up and OWE helped you a great deal by answering the more productive question, "What type of blade is best for cutting leather?"
Cutting anything is interesting because (among other things) performance is a combination of 4 things: the goal or desired outcome, the technique or skill of the cutter, the blade of the knife and the material being cut.
Here's an extreme and somewhat off the wall example... I have an earlier version of this book. It's a cute and fun read.
Central to this guy's goal is making nice controlled curls in wood. He discusses both the technique of making these cuts and his preferred edge geometry, which in this case is a convexed edge which he asserts (and I agree) is necessary for making curls with good control.
My point in raising this seemingly irrelevant example is to point out that what constitutes a "quality" cut very much depends on the situation; what is the goal and what's being cut?
There are several problems with discussing these things on the internet, which leads to the confusion you're experiencing. The most common sits at the core of the difference between pure science and good engineering. Science is all about simplification and control of variables and ends up making very narrowly applicable statements. Thorny engineering problems, like knife performance, often have a complex set of variables that can't be separated or controlled. Science is important to good engineering but really good engineers also understand the limits of tightly constrained scientific claims and are careful not to
over apply the results in situations where they don't apply.
Most people on internet forums are not highly trained engineers and often take experimental results and wrongly try apply them in situations where the tightly controlled preconditions aren't met. In the 90s, back in the usenet days, there was a running joke on rec.skiing called "the physics of skiing" thread. If you point Google at any cycling forum and search for "tire tests", you'll see the same thing over and over. The central confusion is that of amateurs not understanding the limits of some controlled test and then bickering about the applicability in some situation.
When dealing with complex engineering problems, I'm a firm believer in respecting time tested solutions as a starting point. Then start experimenting off of that. Want to know the fastest bike tire for racing on cobble stones? Don't ask about threads per inch on tire casings (the equivalent to toothy vs polished edges). Don't ask about drum based roll downs tests for the rolling resistance (the equivalent to CARTA or other cutting tests). Instead, do what OWE did and ask, "What tires are most commonly on the podium of the Paris-Rubaix?", or in this context, "What do dedicated leather knives look like?" That's a really good engineering move.
Please note, I'm not dismissing cutting tests, or discussions of edge polish or blade grinds. Quite the opposite. All these factors come into play and you should experiment with them. The more you understand them the better you can control
your knives for
your cutting needs.
Circling back to my starting example, Lubkemann, the author of that twig book favors an SAK with a pen blade. He prefers to keep his convexed edge razor sharp to make those controlled curls in wood and to do that, he prefers a blade that can be quickly an often touched up on a pocket stone. Over the course of a project, he finds that to be the most efficient way to keep the sharpest blade working.
I hope something here helps with the confusion issue.
,that's what Id use for this application.